Storage router and method for providing virtual local storage

ABSTRACT

A storage router ( 56 ) and storage network ( 50 ) provide virtual local storage on remote SCSI storage devices ( 60, 62, 64 ) to Fibre Channel devices. A plurality of Fibre Channel devices, such as workstations ( 58 ), are connected to a Fibre Channel transport medium ( 52 ), and a plurality of SCSI storage devices ( 60, 62, 64 ) are connected to a SCSI bus transport medium ( 54 ). The storage router ( 56 ) interfaces between the Fibre Channel transport medium ( 52 ) and the SCSI bus transport medium ( 54 ). The storage router ( 56 ) maps between the workstations ( 58 ) and the SCSI storage devices ( 60, 62, 64 ) and implements access controls for storage space on the SCSI storage devices ( 60, 62, 64 ). The storage router ( 56 ) then allows access from the workstations ( 58 ) to the SCSI storage devices ( 60, 62, 64 ) using native low level, block protocol in accordance with the mapping and the access controls.

TECHNICAL FIELD OF THE INVENTION

[0001] This invention relates in general to network storage devices, andmore particularly to a storage router and method for providing virtuallocal storage on remote SCSI storage devices to Fibre Channel devices.

BACKGROUND OF THE INVENTION

[0002] Typical storage transport mediums provide for a relatively smallnumber of devices to be attached over relatively short distances. Onesuch transport medium is a Small Computer System Interface (SCSI)protocol, the structure and operation of which is generally well knownas is described, for example, in the SCSI-1, SCSI-2 and SCSI-3specifications. High speed serial interconnects provide enhancedcapability to attach a large number of high speed devices to a commonstorage transport medium over large distances. One such serialinterconnect is Fibre Channel, the structure and operation of which isdescribed, for example, in Fibre Channel Physical and SignalingInterface (FC-PH), ANSI X3.230 Fibre Channel Arbitrated Loop (FC-AL),and ANSI X3.272 Fibre Channel Private Loop Direct Attach (FC-PLDA).

[0003] Conventional computing devices, such as computer workstations,generally access storage locally or through network interconnects. Localstorage typically consists of a disk drive, tape drive, CD-ROM drive orother storage device contained within, or locally connected to theworkstation. The workstation provides a file system structure, thatincludes security controls, with access to the local storage devicethrough native low level, block protocols. These protocols map directlyto the mechanisms used by the storage device and consist of datarequests without security controls. Network interconnects typicallyprovide access for a large number of computing devices to data storageon a remote network server. The remote network server provides filesystem structure, access control, and other miscellaneous capabilitiesthat include the network interface. Access to data through the networkserver is through network protocols that the server must translate intolow level requests to the storage device. A workstation with access tothe server storage must translate its file system protocols into networkprotocols that are used to communicate with the server. Consequently,from the perspective of a workstation, or other computing device,seeking to access such server data, the access is much slower thanaccess to data on a local storage device.

SUMMARY OF THE INVENTION

[0004] In accordance with the present invention, a storage router andmethod for providing virtual local storage on remote SCSI storagedevices to Fibre Channel devices are disclosed that provide advantagesover conventional network storage devices and methods.

[0005] According to one aspect of the present invention, a storagerouter and storage network provide virtual local storage on remote SCSIstorage devices to Fibre Channel devices. A plurality of Fibre Channeldevices, such as workstations, are connected to a Fibre Channeltransport medium, and a plurality of SCSI storage devices are connectedto a SCSI bus transport medium. The storage router interfaces betweenthe Fibre Channel transport medium and the SCSI bus transport medium.The storage router maps between the workstations and the SCSI storagedevices and implements access controls for storage space on the SCSIstorage devices. The storage router then allows access from theworkstations to the SCSI storage devices using native low level, blockprotocol in accordance with the mapping and the access controls.

[0006] According to another aspect of the present invention, virtuallocal storage on remote SCSI storage devices is provided to FibreChannel devices. A Fibre Channel transport medium and a SCSI bustransport medium are interfaced with. A configuration is maintained forSCSI storage devices connected to the SCSI bus transport medium. Theconfiguration maps between Fibre Channel devices and the SCSI storagedevices and implements access controls for storage space on the SCSIstorage devices. Access is then allowed from Fibre Channel initiatordevices to SCSI storage devices using native low level, block protocolin accordance with the configuration.

[0007] A technical advantage of the present invention is the ability tocentralize local storage for networked workstations without any cost ofspeed or overhead. Each workstation access its virtual local storage asif it work locally connected. Further, the centralized storage devicescan be located in a significantly remote position even in excess of tenkilometers as defined by Fibre Channel standards.

[0008] Another technical advantage of the present invention is theability to centrally control and administer storage space for connectedusers without limiting the speed with which the users can access localdata. In addition, global access to data, backups, virus scanning andredundancy can be more easily accomplished by centrally located storagedevices.

[0009] A further technical advantage of the present invention isproviding support for SCSI storage devices as local storage for FibreChannel hosts. In addition, the present invention helps to provideextended capabilities for Fibre Channel and for management of storagesubsystems.

BRIEF DESCRIPTION OF THE DRAWINGS

[0010] A more complete understanding of the present invention and theadvantages thereof may be acquired by referring to the followingdescription taken in conjunction with the accompanying drawings, inwhich like reference numbers indicate like features, and wherein:

[0011]FIG. 1 is a block diagram of a conventional network that providesstorage through a network server;

[0012]FIG. 2 is a block diagram of one embodiment of a storage networkwith a storage router that provides global access and routing;

[0013]FIG. 3 is a block diagram of one embodiment of a storage networkwith a storage router that provides virtual local storage;

[0014]FIG. 4 is a block diagram of one embodiment of the storage routerof FIG. 3; and

[0015]FIG. 5 is a block diagram of one embodiment of data flow withinthe storage router of FIG. 4.

DETAILED DESCRIPTION OF THE INVENTION

[0016]FIG. 1 is a block diagram of a conventional network, indicatedgenerally at 10, that provides access to storage through a networkserver. As shown, network 10 includes a plurality of workstations 12interconnected with a network server 14 via a network transport medium16. Each workstation 12 can generally comprise a processor, memory,input/output devices, storage devices and a network adapter as well asother common computer components. Network server 14 uses a SCSI bus 18as a storage transport medium to interconnect with a plurality ofstorage devices 20 (tape drives, disk drives, etc.). In the embodimentof FIG. 1, network transport medium 16 is an network connection andstorage devices 20 comprise hard disk drives, although there arenumerous alternate transport mediums and storage devices.

[0017] In network 10, each workstation 12 has access to its localstorage device as well as network access to data on storage devices 20.The access to a local storage device is typically through native lowlevel, block protocols. On the other hand, access by a workstation 12 tostorage devices 20 requires the participation of network server 14 whichimplements a file system and transfers data to workstations 12 onlythrough high level file system protocols. Only network server 14communicates with storage devices 20 via native low level, blockprotocols. Consequently, the network access by workstations 12 throughnetwork server 14 is slow with respect to their access to local storage.In network 10, it can Also be a logistical problem to centrally manageand administer local data distributed across an organization, includingaccomplishing tasks such as backups, virus scanning and redundancy.

[0018]FIG. 2 is a block diagram of one embodiment of a storage network,indicated generally at 30, with a storage router that provides globalaccess and routing. This environment is significantly different fromthat of FIG. 1 in that there is no network server involved. In FIG. 2, aFibre Channel high speed serial transport 32 interconnects a pluralityof workstations 36 and storage devices 38. A SCSI bus storage transportmedium interconnects workstations 40 and storage devices 42. A storagerouter 44 then serves to interconnect these mediums and provide deviceson either medium global, transparent access to devices on the othermedium. Storage router 44 routes requests from initiator devices on onemedium to target devices on the other medium and routes data between thetarget and the initiator. Storage router 44 can allow initiators andtargets to be on either side. In this manner, storage router 44 enhancesthe functionality of Fibre Channel 32 by providing access, for example,to legacy SCSI storage devices on SCSI bus 34. In the embodiment of FIG.2, the operation of storage router 44 can be managed by a managementstation 46 connected to the storage router via a direct serialconnection.

[0019] In storage network 30, any workstation 36 or workstation 40 canaccess any storage device 38 or storage device 42 through native lowlevel, block protocols, and vice versa. This functionality is enabled bystorage router 44 which routes requests and data as a generic transportbetween Fibre Channel 32 and SCSI bus 34. Storage router 44 uses tablesto map devices from one medium to the other and distributes requests anddata across Fibre Channel 32 and SCSI bus 34 without any security accesscontrols. Although this extension of the high speed serial interconnectprovided by Fibre Channel 32 is beneficial, it is desirable to providesecurity controls in addition to extended access to storage devicesthrough a native low level, block protocol.

[0020]FIG. 3 is a block diagram of one embodiment of a storage network,indicated generally at 50, with a storage router that provides virtuallocal storage. Similar to that of FIG. 2, storage network 50 includes aFibre Channel high speed serial interconnect 52 and a SCSI bus 54bridged by a storage router 56. Storage router 56 of FIG. 3 provides fora large number of workstations 58 to be interconnected on a commonstorage transport and to access common storage devices 60, 62 and 64through native low level, block protocols.

[0021] According to the present invention, storage router 56 hasenhanced functionality to implement security controls and routing suchthat each workstation 58 can have access to a specific subset of theoverall data stored in storage devices 60, 62 and 64. This specificsubset of data has the appearance and characteristics of local storageand is referred to herein as virtual local storage. Storage router 56allows the configuration and modification of the storage allocated toeach attached workstation 58 through the use of mapping tables or othermapping techniques.

[0022] As shown in FIG. 3, for example, storage device 60 can beconfigured to provide global data 65 which can be accessed by allworkstations 58. Storage device 62 can be configured to providepartitioned subsets 66, 68, 70 and 72, where each partition is allocatedto one of the workstations 58 (workstations A, B, C and D). Thesesubsets 66, 68, 70 and 72 can only be accessed by the associatedworkstation 58 and appear to the associated workstation 58 as localstorage accessed using native low level, block protocols. Similarly,storage device 64 can be allocated as storage for the remainingworkstation 58 (workstation E).

[0023] Storage router 56 combines access control with routing such thateach workstation 58 has controlled access to only the specifiedpartition of storage device 62 which forms virtual local storage for theworkstation 58. This access control allows security control for thespecified data partitions. Storage router 56 allows this allocation ofstorage devices 60, 62 and 64 to be managed by a management station 76.Management station 76 can connect directly to storage router 56 via adirect connection or, alternately, can interface with storage router 56through either Fibre Channel 52 or SCSI bus 54. In the latter case,management station 76 can be a workstation or other computing devicewith special rights such that storage router 56 allows access to mappingtables and shows storage devices 60, 62 and 64 as they exist physicallyrather than as they have been allocated.

[0024] The environment of FIG. 3 extends the concept of a singleworkstation having locally connected storage devices to a storagenetwork 50 in which workstations 58 are provided virtual local storagein a manner transparent to workstations 58. Storage router 56 providescentralized control of what each workstation 58 sees as its local drive,as well as what data it sees as global data accessible by otherworkstations 58. Consequently, the storage space considered by theworkstation 58 to be its local storage is actually a partition (i.e.,logical storage definition) of a physically remote storage device 60, 62or 64 connected through storage router 56. This means that similarrequests from workstations 58 for access to their local storage devicesproduce different accesses to the storage space on storage devices 60,62 and 64. Further, no access from a workstation 58 is allowed to thevirtual local storage of another workstation 58.

[0025] The collective storage provided by storage devices 60, 62 and 64can have blocks allocated by programming means within storage router 56.To accomplish this function, storage router 56 can include routingtables and security controls that define storage allocation for eachworkstation 58. The advantages provided by implementing virtual localstorage in centralized storage devices include the ability to docollective backups and other collective administrative functions moreeasily. This is accomplished without limiting the performance ofworkstations 58 because storage access involves native low level, blockprotocols and does not involve the overhead of high level protocols andfile systems required by network servers.

[0026]FIG. 4 is a block diagram of one embodiment of storage router 56of FIG. 3. Storage router 56 can comprise a Fibre Channel controller 80that interfaces with Fibre Channel 52 and a SCSI controller 82 thatinterfaces with SCSI bus 54. A buffer 84 provides memory work space andis connected to both Fibre Channel controller 80 and to SCSI controller82. A supervisor unit 86 is connected to Fibre Channel controller 80,SCSI controller 82 and buffer 84. Supervisor unit 86 comprises amicroprocessor for controlling operation of storage router 56 and tohandle mapping and security access for requests between Fibre Channel 52and SCSI bus 54.

[0027]FIG. 5 is a block diagram of one embodiment of data flow withinstorage router 56 of FIG. 4. As shown, data from Fibre Channel 52 isprocessed by a Fibre Channel (FC) protocol unit 88 and placed in a FIFOqueue 90. A direct memory access (DMA) interface 92 then takes data outof FIFO queue 90 and places it in buffer 84. Supervisor unit 86processes the data in buffer 84 as represented by supervisor processing93. This processing involves mapping between Fibre Channel 52 and SCSIbus 54 and applying access controls and routing functions. A DMAinterface 94 then pulls data from buffer 84 and places it into a buffer96. A SCSI protocol unit 98 pulls data from buffer 96 and communicatesthe data on SCSI bus 54. Data flow in the reverse direction, from SCSIbus 54 to Fibre Channel 52, is accomplished in a reverse manner.

[0028] The storage router of the present invention is a bridge devicethat connects a Fibre Channel link directly to a SCSI bus and enablesthe exchange of SCSI command set information between application clientson SCSI bus devices and the Fibre Channel links. Further, the storagerouter applies access controls such that virtual local storage can beestablished in remote SCSI storage devices for workstations on the FibreChannel link. In one embodiment, the storage router provides aconnection for Fibre Channel links running the SCSI Fibre ChannelProtocol (FCP) to legacy SCSI devices attached to a SCSI bus. The FibreChannel topology is typically an Arbitrated Loop (FC_AL).

[0029] In part, the storage router enables a migration path to FibreChannel based, serial SCSI networks by providing connectivity for legacySCSI bus devices. The storage router can be attached to a Fibre ChannelArbitrated Loop and a SCSI bus to support a number of SCSI devices.Using configuration settings, the storage router can make the SCSI busdevices available on the Fibre Channel network as FCP logical units.Once the configuration is defined, operation of the storage router istransparent to application clients. In this manner, the storage routercan form an integral part of the migration to new Fibre Channel basednetworks while providing a means to continue using legacy SCSI devices.

[0030] In one implementation (not shown), the storage router can be arack mount or free standing device with an internal power supply. Thestorage router can have a Fibre Channel and SCSI port, and a standard,detachable power cord can be used, the FC connector can be a copper DB9connector, and the SCSI connector can be a 68-pin type. Additionalmodular jacks can be provided for a serial port and a 802.3 10BaseTport, i.e. twisted pair Ethernet, for management access. The SCSI portof the storage router an support SCSI direct and sequential accesstarget devices and can support SCSI initiators, as well. The FibreChannel port can interface to SCSI-3 FCP enabled devices and initiators.

[0031] To accomplish its functionality, one implementation of thestorage router uses: a Fibre Channel interface based on theHEWLETT-PACKARD TACHYON HPFC-5000 controller and a GLM media interface;an Intel 80960RP processor, incorporating independent data and programmemory spaces, and associated logic required to implement a stand aloneprocessing system; and a serial port for debug and system configuration.Further, this implementation includes a SCSI interface supportingFast-20 based on the SYMBIOS 53C8xx series SCSI controllers, and anoperating system based upon the WIND RIVERS SYSTEMS VXWORKS or IXWORKSkernel, as determined by design. In addition, the storage routerincludes software as required to control basic functions of the variouselements, and to provide appropriate translations between the FC andSCSI protocols.

[0032] The storage router has various modes of operation that arepossible between FC and SCSI target and initiator combinations. Thesemodes are: FC Initiator to SCSI Target; SCSI Initiator to FC Target;SCSI Initiator to SCSI Target; and FC Initiator to FC Target. The firsttwo modes can be supported concurrently in a single storage routerdevice are discussed briefly below. The third mode can involve twostorage router devices back to back and can serve primarily as a deviceto extend the physical distance beyond that possible via a direct SCSIconnection. The last mode can be used to carry FC protocols encapsulatedon other transmission technologies (e.g. ATM, SONET), or to act as abridge between two FC loops (e.g. as a two port fabric).

[0033] The FC Initiator to SCSI Target mode provides for the basicconfiguration of a server using Fibre Channel to communicate with SCSItargets. This mode requires that a host system have an FC attacheddevice and associated device drivers and software to generate SCSI-3 FCPrequests. This system acts as an initiator using the storage router tocommunicate with SCSI target devices. The SCSI devices supported caninclude SCSI-2 compliant direct or sequential access (disk or tape)devices. The storage router serves to translate command and statusinformation and transfer data between SCSI-3 FCP and SCSI-2, allowingthe use of standard SCSI-2 devices in a Fibre Channel environment.

[0034] The SCSI Initiator to FC Target mode provides for theconfiguration of a server using SCSI-2 to communicate with Fibre Channeltargets. This mode requires that a host system has a SCSI-2 interfaceand driver software to control SCSI-2 target devices. The storage routerwill connect to the SCSI-2 bus and respond as a target to multipletarget IDs. Configuration information is required to identify the targetIDs to which the bridge will respond on the SCSI-2 bus. The storagerouter then translates the SCSI-2 requests to SCSI-3 FCP requests,allowing the use of FC devices with a SCSI host system. This will alsoallow features such as a tape device acting as an initiator on the SCSIbus to provide full support for this type of SCSI device.

[0035] In general, user configuration of the storage router will beneeded to support various functional modes of operation. Configurationcan be modified, for example, through a serial port or through anEthernet port via SNMP (simple network management protocol) or a Telnetsession. Specifically, SNMP manageability can be provided via an 802.3Ethernet interface. This can provide for configuration changes as wellas providing statistics and error information. Configuration can also beperformed via TELNET or RS-232 interfaces with menu driven commandinterfaces. Configuration information can be stored in a segment offlash memory and can be retained across resets and power off cycles.Password protection can also be provided.

[0036] In the first two modes of operation, addressing information isneeded to map from FC addressing to SCSI addressing and vice versa. Thiscan be ‘hard’ configuration data, due to the need for addressinformation to be maintained across initialization and partialreconfigurations of the Fibre Channel address space. In an arbitratedloop configuration, user configured addresses will be needed for AL_PAsin order to insure that known addresses are provided between loopreconfigurations.

[0037] With respect to addressing, FCP and SCSI 2 systems employdifferent methods of addressing target devices. Additionally, theinclusion of a storage router means that a method of translating deviceIDs needs to be implemented. In addition, the storage router can respondto commands without passing the commands through to the oppositeinterface. This can be implemented to allow all generic FCP and SCSIcommands to pass through the storage router to address attached devices,but allow for configuration and diagnostics to be performed directly onthe storage router through the FC and SCSI interfaces.

[0038] Management commands are those intended to be processed by thestorage router controller directly. This may include diagnostic, mode,and log commands as well as other vendor-specific commands. Thesecommands can be received and processed by both the FCP and SCSIinterfaces, but are not typically bridged to the opposite interface.These commands may also have side effects on the operation of thestorage router, and cause other storage router operations to change orterminate.

[0039] A primary method of addressing management commands though the FCPand SCSI interfaces can be through peripheral device type addressing.For example, the storage router can respond to all operations addressedto logical unit (LUN) zero as a controller device. Commands that thestorage router will support can include INQUIRY as well asvendor-specific management commands. These are to be generallyconsistent with SCC standard commands.

[0040] The SCSI bus is capable of establishing bus connections betweentargets. These targets may internally address logical units. Thus, theprioritized addressing scheme used by SCSI subsystems can be representedas follows: BUS:TARGET:LOGICAL UNIT. The BUS identification is intrinsicin the configuration, as a SCSI initiator is attached to only one bus.Target addressing is handled by bus arbitration from informationprovided to the arbitrating device. Target addresses are assigned toSCSI devices directly, though some means of configuration, such as ahardware jumper, switch setting, or device specific softwareconfiguration. As such, the SCSI protocol provides only logical unitaddressing within the Identify message. Bus and target information isimplied by the established connection.

[0041] Fibre Channel devices within a fabric are addressed by a uniqueport identifier. This identifier is assigned to a port during certainwell-defined states of the FC protocol. Individual ports are allowed toarbitrate for a known, user defined address. If such an address is notprovided, or if arbitration for a particular user address fails, theport is assigned a unique address by the FC protocol. This address isgenerally not guaranteed to be unique between instances. Variousscenarios exist where the AL-PA of a device will change, either afterpower cycle or loop reconfiguration.

[0042] The FC protocol also provides a logical unit address field withincommand structures to provide addressing to devices internal to a port.The FCP_CMD payload specifies an eight byte LUN field. Subsequentidentification of the exchange between devices is provided by the FQXID(Fully Qualified Exchange ID).

[0043] FC ports can be required to have specific addresses assigned.Although basic functionality is not dependent on this, changes in theloop configuration could result in disk targets changing identifierswith the potential risk of data corruption or loss. This configurationcan be straightforward, and can consist of providing the device aloop-unique ID (AL_PA) in the range of “01h” to “EFh”. Storage routerscould be shipped with a default value with the assumption that mostconfigurations will be using single storage routers and no other devicesrequesting the present ID. This would provide a minimum amount ofinitial configuration to the system administrator. Alternately, storagerouters could be defaulted to assume any address so that configurationsrequiring multiple storage routers on a loop would not require that theadministrator assign a unique ID to the additional storage routers.

[0044] Address translation is needed where commands are issued in thecases FC Initiator to SCSI Target and SCSI Initiator to FC Target.Target responses are qualified by the FQXID and will retain thetranslation acquired at the beginning of the exchange. This preventsconfiguration changes occurring during the course of execution of acommand from causing data or state information to be inadvertentlymisdirected. Configuration can be required in cases of SCSI Initiator toFC Target, as discovery may not effectively allow for FCP targets toconsistently be found. This is due to an FC arbitrated loop supportingaddressing of a larger number of devices than a SCSI bus and thepossibility of FC devices changing their AL-PA due to device insertionor other loop initialization.

[0045] In the direct method, the translation to BUS:TARGET:LUN of theSCSI address information will be direct. That is, the values representedin the FCP LUN field will directly map to the values in effect on theSCSI bus. This provides a clean translation and does not require SCSIbus discovery. It also allows devices to be dynamically added to theSCSI bus without modifying the address map. It may not allow forcomplete discovery by FCP initiator devices, as gaps between deviceaddresses may halt the discovery process. Legacy SCSI device driverstypically halt discovery on a target device at the first unoccupied LUN,and proceed to the next target. This would lead to some devices notbeing discovered. However, this allows for hot plugged devices and otherchanges to the loop addressing.

[0046] In the ordered method, ordered translation requires that thestorage router perform discovery on reset, and collapses the addresseson the SCSI bus to sequential FCP LUN values. Thus, the FCP LUN values0-N can represent N+1 SCSI devices, regardless of SCSI address values,in the order in which they are isolated during the SCSI discoveryprocess. This would allow the FCP initiator discovery process toidentify all mapped SCSI devices without further configuration. This hasthe limitation that hot-plugged devices will not be identified until thenext reset cycle. In this case, the address may also be altered as well.

[0047] In addition to addressing, according to the present invention,the storage router provides configuration and access controls that causecertain requests from FC Initiators to be directed to assigned virtuallocal storage partitioned on SCSI storage devices. For example, the samerequest for LUN 0 (local storage) by two different FC Initiators can bedirected to two separate subsets of storage. The storage router can usetables to map, for each initiator, what storage access is available andwhat partition is being addressed by a particular request. In thismanner, the storage space provided by SCSI storage devices can beallocated to FC initiators to provide virtual local storage as well asto create any other desired configuration for secured access.

[0048] Although the present invention has been described in detail, itshould be understood that various changes, substitutions, andalterations can be made hereto without departing from the spirit andscope of the invention as defined by the appended claims.

What is claimed is:
 1. A storage router for providing virtual localstorage on remote SCSI storage devices to Fibre Channel devices,comprising: a buffer providing memory work space for the storage router;a Fibre Channel controller operable to connect to and interface with aFibre Channel transport medium; a SCSI controller operable to connect toand interface with a SCSI bus transport medium; and a supervisor unitcoupled to the Fibre Channel controller, the SCSI controller and thebuffer, the supervisor unit operable: to maintain a configuration forSCSI storage devices connected to the SCSI bus transport medium thatmaps between Fibre Channel devices and SCSI storage devices and thatimplements access controls for storage space on the SCSI storagedevices; and to process data in the buffer to interface between theFibre Channel controller and the SCSI controller to allow access fromFibre Channel initiator devices to SCSI storage devices using native lowlevel, block protocol in accordance with the configuration.
 2. Thestorage router of claim 1, wherein the configuration maintained by thesupervisor unit includes an allocation of subsets of storage space toassociated Fibre Channel devices, wherein each subset is only accessibleby the associated Fibre Channel device.
 3. The storage router of claim2, wherein the Fibre Channel devices comprise workstations.
 4. Thestorage router of claim 2, wherein the SCSI storage devices comprisehard disk drives.
 5. The storage router of claim 1, wherein the FibreChannel controller comprises: a Fibre Channel (FC) protocol unitoperable to connect to the Fibre Channel transport medium; afirst-in-first-out queue coupled to the Fibre Channel protocol unit; anda direct memory access (DMA) interface coupled to the first-in-first-outqueue and to the buffer.
 6. The storage router of claim 1, wherein theSCSI controller comprises: a SCSI protocol unit operable to connect tothe SCSI bus transport medium; an internal buffer coupled to the SCSIprotocol unit; and a direct memory access (DMA) interface coupled to theinternal buffer and to the buffer of the storage router.
 7. A storagenetwork, comprising: a Fibre Channel transport medium; a SCSI bustransport medium; a plurality of workstations connected to the FibreChannel transport medium; a plurality of SCSI storage devices connectedto the SCSI bus transport medium; and a storage router interfacingbetween the Fibre Channel transport medium and the SCSI bus transportmedium, the storage router providing virtual local storage on the SCSIstorage devices to the workstations and operable: to map between theworkstations and the SCSI storage devices; to implement access controlsfor storage space on the SCSI storage devices; and to allow access fromthe workstations to the SCSI storage devices using native low level,block protocol in accordance with the mapping and access controls. 8.The storage network of claim 7, wherein the access controls include anallocation of subsets of storage space to associated workstations,wherein each subset is only accessible by the associated workstation. 9.The storage network of claim 7, wherein the SCSI storage devicescomprise hard disk drives.
 10. The storage network of claim 7, whereinthe storage router comprises: a buffer providing memory work space forthe storage router; a Fibre Channel controller operable to connect toand interface with a Fibre Channel transport medium, the Fibre Channelcontroller further operable to pull outgoing data from the buffer and toplace incoming data into the buffer; a SCSI controller operable toconnect to and interface with a SCSI bus transport medium, the SCSIcontroller further operable to pull outgoing data from the buffer and toplace incoming data into the buffer; and a supervisor unit coupled tothe Fibre Channel controller, the SCSI controller and the buffer, thesupervisor unit operable: to maintain a configuration for the SCSIstorage devices that maps between Fibre Channel devices and SCSI storagedevices and that implements the access controls for storage space on theSCSI storage devices; and to process data in the buffer to interfacebetween the Fibre Channel controller and the SCSI controller to allowaccess from workstations to SCSI storage devices in accordance with theconfiguration.
 11. A method for providing virtual local storage onremote SCSI storage devices to Fibre Channel devices, comprising:interfacing with a Fibre Channel transport medium; interfacing with aSCSI bus transport medium; maintaining a configuration for SCSI storagedevices connected to the SCSI bus transport medium that maps betweenFibre Channel devices and the SCSI storage devices and that implementsaccess controls for storage space on the SCSI storage devices; andallowing access from Fibre Channel initiator devices to SCSI storagedevices using native low level, block protocol in accordance with theconfiguration.
 12. The method of claim 11, wherein maintaining theconfiguration includes allocating subsets of storage space to associatedFibre Channel devices, wherein each subset is only accessible by theassociated Fibre Channel device.
 13. The method of claim 12, wherein theFibre Channel devices comprise workstations.
 14. The method of claim 12,wherein the SCSI storage devices comprise hard disk drives.